The Stephen Lawrence inquiry report is expected to recommend a police investigation into whether any of the five murder suspects committed perjury when they gave evidence last year.

The Guardian understands that legal advice given to the inquiry team suggests there are grounds for charges.

Sir William Macpherson, the inquiry chairman, who delivered his report to the Home Secretary this week, indicated at the start of the hearings that the five could be prosecuted if they had told lies.

During the evidence of Jamie Acourt, one of the five, a clearly agitated Sir William intervened with this warning: 'You have immunity in connection with the matters which have been investigated in the past but if you commit perjury you may be prosecuted."

Acourt had denied carrying knives in public and being a racist. In another exchange, Gary Dobson admitted that a stun gun owned by the young men carried an electric shock, which Neil Acourt had denied.

A conviction for perjury can carry a sentence of up to seven years.

Such a prosecution may be the only opportunity left to bring some or all of the five into a court of law to answer questions.

The private prosecution brought by the Lawrence family collapsed before the three then charged were called to the witness box. Later, at the inquest, all five declined to answer questions on legal advice.

The police failure to bring anyone to justice - including the mysterious sixth blond man - will be at the centre of Sir William's criticisms with a finding that institutional racism was a pervasive hindrance to more effective action.

Intense and contradictory media speculation about whether the report will criticise the Metropolitan Police Commissioner, Sir Paul Condon, continued yesterday with senior Scotland Yard sources insisting that Sir Paul has not been formally warned of any personal censure.

Last week, after reports that Home Office officials wanted him to go, it is understood that Jack Straw, the Home Secretary, contacted the commissioner to reassure him that those were not his views. Some Scotland Yard sources believe there is a whispering campaign against Sir Paul, however, and that briefings suggesting he will have to resign have been given.

Many in the Home Office have been predicting for the past two weeks that Sir Paul will be pressed to resign before his seven-year contract ends next January. Sir Paul is anxious to remain in office until next year.

Scotland Yard admitted there had been an exchange of letters between the inquiry and Sir Paul, but declined to discuss them. It is understood that the letters asked Sir Paul to elucidate police practice and procedure. He has always said that if he were to face serious criticism in the report he would 'consider his position'.

The confusion over whether or not Sir Paul had received letters warning him that he was to be censured may have arisen because letters of criticism were sent to individual officers, and because the Met's senior management has been criticised for a number of failings.

They include not only a savaging of the management of the murder investigation but also of the internal review which the inquiry dismissed as a whitewash. Its author, Chief Supt Roderick Barker, was described as an unreliable witness.The Met has not sought to defend the review, which concluded that the murder had been investigated competently and sensitively. It was commissioned by Deputy Assistant Commissioner David Osland and endorsed by Sir Paul.

In its response to the inquiry the Met admitted that the review 'purported to have subjected the first [murder] investigation to intense scrutiny when in fact it had not'. But its response to the inquiry added: 'Chief police officers were misled at the time of the production of the review and endorsed it in good faith.'